Hose



W. HAAS Oct. 19, 1965 HOSE Ori inal Filed April ll. 1957 um m Sdi wm .VQ x United States Patent C) 3,212,528 HOSE Willard Haas, Cuyahoga Falls,Ohio, assignor to The B. F. Goodrich Company, New York, N.Y., acorporation of New York Continuation of applications Ser. No. 652,232,Apr. 11,

1957, and Ser. No. 157,448, Dec. 6, 1961. This application Feb. 13,1964, Ser. No. 344,759

3 Claims. (Cl. 13S-130) This invention relates to the manufacture offlexible wire-reinforced rubber hose especially suited for highpressurehydraulic systems. rIThe invention includes both a novel hoseconstruction and a method for making such hose. 'Ihis application is acontinuation of my pending application Serial No. 652,232 tiled April11, 1957, now abandoned, Iand my pending application Serial No. 157,448,filed December 6, 1961, also now abandoned.

Hose customarily used for hydraulic systems has been reinforced withbraided wires to impart the requisite burst resistance without undulystitfening the hose. A significant disadvantage of a braided Wirereinforcement in a hose subjected to high pressures (for example 3,000pounds per square inch or more), however, is that braided wi-res arecrimped or curved sharply on each other so that pressure :surges offluid within the Ihose cause the wires to rub and flex about each otherat each plait. Repeated rubbing and flexure weakens the wires andmaterially limits the useful life of the hose.

The disadvantage of braids in this respect can be obviated byreinforcing a hose with wire plies in which the wires are disposed inparallel helical convolutions. Prior to this invention, however, highpressure hose made with helically wrapped wire pl-ies has beencommercially unacceptable because it could not be cut without having thewire ends at the severance plane flare wildly from their respectiveplies making it ditiicult or impossible to attach a fitting to the cutend.

Moreover, since wires having satisfactory tensile strength for thispurpose is very fine, and highly resilient, it has been very diicult towrap these wires on a hose carcass in uniform convolutions and at thesame time avoid mutilating the underlying rubber carcass material.

In accordance with this invention commercially satisfactory hose isprovided embodying reinforcing plies formed of a multiplicity ofindividual resilient wires disposed in helical convolutions.Objectionable aring of the wire ends at a severance plane is whollyeliminated. In the hose provided by this invention two or moreconcentric helical Wire plies of opposite hand are included in the wallof the hose. At least the outermost wire ply is in resilient grippingengagement with the underlying adjacent portions of the wall of thehose. Thus, wherever this hose is cut, the wire ends do not flare but,on the contrary, tend to con'strict the hose end slightly. In makingthis Ihose the wires of at least the outer ply are formed to impart tothem an inherent tendency to take the shape of a helix the diameter ofwhich is preferably somewhat less than the diameter of the convolutionsin which the wires lare in fact wrapped on the hose carcass and thepitch of which is also preferably less than, but at least does notsubstantially exceed the pitch of the convolutions in which the wiresare in fact wrapped on the hose carcass. The inner wire plies also maybe formed to exert constricting pressure on their respective underlyingportions of the hose carcass. Successive wire plies are insulated fromeach other by rubber or rubber-treated fabric, plastics or other exiblematerial. The term rubber as used 'herein includes natural rubber andthe various synthetic materials having, or which may be compounded toimpart, the characteristic flexibility and extensibility of rubber. Therub- 3,212,528 Patented Oct. 19, 1965 ice ber materials used inhydraulic hose are normally oilresistant rubbers known in the art asneoprene or nitrile rubber compounds.

Optionally, in some types of hose, the innermost wire ply may -be formedso that it tends to expand radially, thereby exerting a radially outwardcompressive force on the surrounding portions of the hose carcassinstead of constricting pressure as noted previously. Normally theinnermost wire ply is positioned closely adjacent a central fluid-tightrubber or plastic tube extending through the hose. Accordingly, byforming the innermost ply so that it is somewhat expansible, the wireends at a severance plane tend to expand slightly radially outwardly ofthe tube, thereby avoiding distortion of the tube and possibleobstruction of the passage through the hose. Also, certain types ofcouplings are attached to the hose end by inserting the coupling shankconcentrically between the first ply and the tube forming the center ofthe hose. Making the first ply slightly expansible facilitates thisassembly.

In the preferred manufacturing procedure for the hose of this inventionthe multiplicity of individual wires which are integrated to form eachply are trained under equal uniform tension from a wire supply and a-reatt-ached to the surface of the portion of the hose carcass on which theply is to be formed. The portions of the wires near the hose car-cassare gathered into an array converging concentrically toward the hosecarcass and as the array approaches the location where it isprogressively wrapped on the carcass the converging portions of thewires are shaped to a helical curvature to either grip the hose carcassor to expand from the hose carcass, as the case may be. The shaping iseffected by bending the converging portions of the wires over suitablycontoured surfaces under sufficient tension to cold work all the wiressimultaneously and impart to each an inherent tendency to take the shapeof a helix of the particular size desired.

Hose embodying this invention has been found to be particularly usefulfor hydraulic systems where fluid pressures are as high as 15,000 poundsper square inch or more. It undergoes practically no twisting orsignificant dimensional changes under pressure. Moreover, it has beenfound to possess exceptionally better impulse fatigue life (i,e., burstresistance under service conditions where it is subjected to frequentextreme pressure surges) than hose of corresponding size with braidedwire reinforcements which has been previously used for this service.

An embodiment of the invention will be further described with referenceto the accompanying drawings. In the drawings:

FIG. 1 shows a hose construction made in accordance with this invention,the component portions of the hose cover being broken away progressivelyto illu-strate the nature of the several components;

FIG. 2 -shows in schematic form equipment which may be advantageouslyused for manufacturing hose in accordance with the method of thisinvention;

FIGS. 2a and 2b are fragmentary detail views of certain parts of theequipment shown in FIG. 2; and

FIG. 3 -is a fragmentary view taken along the line 3-3 of FIG. 2.

Referring to FIG. 1, the hose structure includes a uidtight rubber tube10 surrounded by a wall which includes four wire reinforcing pliesidentified by the reference numerals 12, 13, 14 and 15. The wire pliesare concentrically arranged about the tube 10 and are separated bylayers of rubber or rubber-treated non-metallic fabrics 17, 18, 19, 20and 21. The exterior of the carcass is encased by a rubber cover 22.

Each of the wire plies is composed of a multiplicity of individual finehigh-tensile wires disposed in parallel helical convolutions about thelongitudinal axis of the hose. The helix is of opposite hand insuccessive plies. That is to say, the direction of the helix alternatesin successive wire plies. The Wires are preferably standardmonofilament-ary high-tensile strength cold-drawn spring steel wire. Theso-called music quality wire having a tensile strength at the yieldpoint of about 300,000 to 425,000 pounds per'square inch and rangingfrom about .010 inch to about .030 inch in diameter may be usedadvantageously. With this hose construction the wires may be used in theform in which they are cold drawn at the Wire mills, no cleaning orother treatment normally being required. The wires comprising each plyare preferably packed as close together as possible so that they aresubstantially in'laterally abutting relation. Por development of maximumstrength in high-pressure hydraulic hose, at least 85% of the underlyingsurface should be covered by the wires of each ply. Preferably more thanabout 90% up to 100% of the underlying surface is covered by each ply toobtain maximum burst resistance. It may be convenient to use the samenumber of wires in each ply, and in that case it is evident that in theoutermost plies the wires will be spaced apart slightly more than thewires of the innermost plies because the diameter of the outer plies islarger than the inner plies.

In the hose shown in FIG. 1`, the innermost Wire ply 12 is wrapped upona layer of loosely woven fabric 17 which in turn encloses the rubbertube 10. Since the tube is in an unvulcanized state when the wire pliesare wrapped, the fabric layer 17 protects the tube from being cut orgouged when the first wire ply 12 is wrapped. The fabric 17 is a coarsecloth of about 15 warp threads .per inch and 10 weft threads per inchand is applied over the tube after the tube is washed with a suitablesolvent. It is convenient to slit the fabric 17 to a tape of suitablewidth which is wound helically with its edges abutting, at the sameangle as the wires of the first ply 12. Some of the surface material ofthe tube usually oozes4 or strikes through the meshes of the fabric 17when the first wire ply 12 is applied, to fill the' spaces between theWires and provide an adhesive bond between the tube 1 0 and the firstWire sheath 12 when the hose construction 1s eventually vulcanized.

The several wire plies are insulated one from another. Between the firstwire p'ly 12 and the second wire ply 13, this insulation takes the formof `a layer of rubberized cloth 1. This layer 18 is preferably squarewoven cloth of a relatively fine weave such as 48 warp and 48 weftthreads perV inch, which is impregnated with rubber on both sides bycalendering. It is also conveniently slit to a narrow tape which iswrapped helically in abutting convolutions about the first wire ply 12at the same angle as the second wire ply 13. The cloth 18 binds thewires of the first ply so that those wires can not become displaced fromthe position in which they are laid, which is most important for theinnermost ply since it does not have as much internal support as theouter plies. In some cases rubber alone is adequate for this layer 18.

The third wire ply 14 is insulated from contact with the second wire ply13 by a layer of rubber 19 and the fourth wire ply 15 is insulated fromthe third wire ply 14 by a layer of rubber 20. The insulating rubber 19and are conveniently applied in the form -of a narrow tape which iswound upon their respective plies in abutting convolutions. The wires ofeach ply are wrapped upon their respective insulating layers withsufficient tension to cause some of the rubber material to be squeezedinto the spaces between the wires of both the ply being applied over theinsulating layer and the wire ply underlying the insulating layer. Thusthe rubber insulating layers (and the rubber calendered on the cloth 18)provide a matrix in which the Wires of the plies which they separate areembedded. The thickness of the insulating layers may vary considerably.It is usually desirable to keep these layers rather thin to avoid undulystiffening the hose, and building up unnecessary thickness.

The outer or fourth Wire ply 15 may itself serve as the outer coveringof the hose, or various conventional types of coverings may be used. Inthe hose of FIG. 1 a serving of textile cords 21 such as cotton or nylonis wound helically about the outer wire ply 15. Preferably these cordsare impregnated with a rubber material and may be adhered adequately tothe ply 15 by the rubber material of the insulating layer 20 which issqueezed outwardly between the wires of ply 15. The outer rubber cover22 surrounding the serving 21 may be extruded over the reinforcing pliesor it may be wound on the carcass portion in the form of a tape in themanner conventional in the art. The complete hose carcass may be curedin open :steam vulcanizers in the conventional manner, either exposed orencased in lead or a textile wrapper common to the hose manufacturingart.

In order to avoid objectionable flaring or displacement of the wires ata severance plane, the outer wire ply 15 is applied so that itinherently tends to exert a gripping or constricting resilient pressureon the underlying portions of the hose carcass. This result is obtainedby forming or imparting to each wire of the outer ply an inherenttendency to take the shape of a helix of a size such that the diameterof the neutral lay of each helically shaped wire in this ply would beless than the diameter of the convolutions in which the wire is in factwrapped on the hose carcass, and likewise such that the pitch of theneutral lay of each helically shaped wire would be slightly less thanthe pitch of the Wrapped convolutions. The term neutral lay as usedherein means the helical shape an individual helically-formed wire wouldtake if free from any external deforming forces. The term diameter withreference to the neutral lay means the outer diameter of the wire helixunder strain-free conditions from one side of the helix to a planesurface on which the opposing portions of the convolutions rest.Accordingly the wire ends of the outer ply at a severance plane willremain passive, even when a portion of the outer cover is stripped backfrom the cut ends toattach a coupling or other suitable fitting.

In general, a wire can be formed helically to grip or constrict theunderlying carcass if the spiral length of wire contained in onecomplete convolution of its neutral lay is less than the spiral lengthof wire contained in one complete convolution when wrapped Ion the hosecarcass. However, in the outer ply 15, from which the cover may bestripped near a cut end, it is preferable to shape the wires so that thediameter of their neutral lay i-s less than, or at least does notsubstantially exceed, the diameter of the convolutions in which thewires are wrapped. Similarly the pitch of the neutral lay should begreater than about 50% of the pitch of the wrapped convolutions but notsubstantially greater than the pitch of the wrapped -convolutions toavoid the possibility of having the wire ends thrust outwardly in anaxial direction of the hose when the cover is stripped from the outerply.

In this invention at least the outermost wire ply exerts a gripping orconstricting pressure on the underlying portions of the hose. When -morethan two plies are present it is desirable that two or more of themexert a constricting pressure. In some instances all the plies may be soconstructed that all of them will tend to constrict the underlyinglayers, either equally or to a lesser extent in the first or innermostply or plies. On the other hand, as has already been pointed out, it isadvantageous under certain Conditions to form the innermost or first ply12 so that it tends to expand slightly relative to the underlyingportions of the hose carcass.

'Ilhe forming lof ply 11=2 so .that it tends to expand slightly itsaccomplished by shaping the wires so that the spimal length of onecomplete neutral convolution is slightly longer than the spinal lengthof one complete wrapped conwolutio-n. To :avoid the possibility lofhaving the wire ends thrust outwardly axially when the [hose is cut, itis preferable that the pit-ch of the zconvolutions in the neutral lay isless than or at least docs not substantially exceed the pitch at whichthe convolutions are Wrapped.

As an example of a specilic construction, a hose having tour Wire pliesas described in the foregoing is made with a neoprene tube .10 of 1/zi-nch internal diameter and an outer diameter of 21/32 inch. The fabric17, which is placed between the tube and the rst wire ply I112., is asquare woven cotton fabric containing 'warp ends per inch and 10 `Wettends per inch and is slit to ttorm a tape 1% inches wide. The cloth 118,which is placed between the first and second wire plies 12 4and 13, issquare Woven cotton fabric hav-ing 448 warp ends and 48 weft ends perinch. 'It is irictioned on both sides with rubber and is in fthe form ofa tape 1% inches Wide. The insulation layers 19 and `20, respectively,are rubber having an average thickness of about 0.008 inch and are inthe form of tapes 11/2 inches wide. Each Wire ply contains 99 ends ofmusic quality steel Wire of 0.012 inch diameter. IEach Wire ply isWrapped .at a pitch of 1% inches. The individual Wires of the first Wireply 12 are Wrapped in helices ot 1%6 inch outer diameter at an :angle ofabout 53 to the 'hose The Wires of Ithe second wire ply 13 are Wrappedin helices of 4%4 inch outer diameter at an angle of about 54 to thehose axis. The Wires of the third wire ply 14 are wrapped in helices of4%4 inch outer diameter at an angle of about 56 to the hose axis. TheWires of .the Iiourlth Wire ply 15 are Wrapped in helices of 5%4 inchouter diameter at an angle of about 57 to the hose The individual Wiresof each ply are rormed with an inherent tendency to take ythe shape of ahelix having the diameter of the neutral lay thereof equal to inch andthe pitch of the neutral lay thereof about 60% of the wrapped pitch. Lnthe hose of 4this example each wire ply is in resilient grippingengagement with the underlying adjacent portions or" the hose.

Another hose is made ot identical construction as that of the precedingparagraph except .that the Wires of the first wire ply l112 are formedwith an inherent tendency to take the shape of a helix having a neutrallay thereof of 7A; linch diameter and a pitch of about `80% .of thewrapped pitch. The iirst wire ply accordingly tends to expand `relativeto the underlying adjacent portions of the hose.

Another hose is of the construction described in the foregoing exceptthat the Wires of the lfirst ply '1-2 are termed as noted in thepreceding paragraph with a neutral lay of 1%6 inch diameter and la pitchof about 1%. ln this construction the first ply is neutral. It neithergrips noir expands.

A hose having two Wire plies is made in accordance with the -rst exampleexcept that the two outer Wire plies 14 and 15, and the insulation 19and 20 are omitted, and the rst two plies are wrapped at a slightlygreater pitch so that the rst ply wires are at an `angle of about 54 andthe second ply wires are at an angle of about 56 to the hose axis.Similarly hose having six or eight Wire plies is made in accordance withthe first example by adding the :additional Wire plies :and insulationbetween them.

All the hose ior which examples are given are .suitable t'or duidpressures as as 15,000 pounds per square inch lor more and haveexceptionally :better impulse fatigue lite than hose off correspondingsize with braided wire plies.

The angles at which the Wires of the several plies are wrapped averageabout 55 which is close lo the theoretical resultant `angle at whichIthe I'orces resulting -'from internal pressure tending to expand thehose diametrically and the forces tending to lengthen the hose arebalanced. This results in a vbalanced 'hose construction. In some casesbalance may be obtained by wrapping the Iwires of all plies at thesa-Ine angle but including additional Wires in successive plies, insteadof using an equal number of 6 wires per ply but varying the angle of thewires in successive plies as in the preceding examples.

The adhesion of the insulating layers to their adjoining wire may besomewhat improved by washing the wires yand dipping them in a suitableadhesive to coat the wires i-n accordance with the usual techniques ofbonding .rubber to the metal 4before wrapping them on the hose carcass.Adequate adhesion is norm-ally obtained, however, without such apreliminary treatment of the wire with this construction.

FIGS. 2 and 3 semi-schematically illustrate one form of apparatus usedin manufacturing hose of this type. In these figures, only ltwo Wires Aand B of a Wire ply are shown Ifor clarity. I'Ihe equipment of fFIGS. 2and 3 is described and claimed in fthe patent oi? Willard Haas and MerleF. Fuller, U.S. 3,037,343, :to which reference may be had 'for lcompletedetails about the apparatus. The following discussion summarizes thesalient rfeatures of the apparatus and its mode of operation in makingthe Ihose construction of application.

The equipment includes a mandrel `25 upon which the several wire pliesand rubber and rf-abric materials forming the wall ofthe hose areassembled. The mandrel 4is movable axially by a truck 31 which 'includesa pinion 33 engaged with a horizontal track 32 to propel the truck.'Ilhe mandrel is :also rotated as it is axially advanced by .a chu-ckl34 which is mounted on truck 31 to receive the iront end of themandrel. The chuck 34 is rotated by a motor 35 which also drives gear33. yPreferably the truck includes means (not shown) to vary therotational speed of the chuck so that the pitch at which the wires arelaid may be accurately regulated.

.At the start of the operation of wrapping :a ply, the truck I31 isinitially positioned close to a wire-shaping mechanism 40 with themandrel extending through the central opening zot the mechanism 40.'Each of the wires such as representative wires A and B are trained fromtheir respective supply spools 42 and are threaded through the mechanism40 and secured by tape ror the like (not shown) to a portion of the hosecarcass on the mandrel near the chuck 34. Then the :truck 31 is drivenrightward (as it is viewed in FIG. 2), with its chuck 34 notati-ng atthe desired speed so that the several Wires are pulled trom their spools`42 and through the wire-shaping mechanism `4l) and are wrapped in ahelix against the hose carcass. Each supply spo-ol 42 includes a let-offapparatus (not shown) llor maintaining uniform tension in the wire as itis payed oli the spool. A let-off apparatus or this purpose is morelfully describe-d in the patent loi Ralph F. Cooper, U.S. Patent2,920,840.

Between the spools and the shaping mechanism 40 the wires pass through aWire `gathering plate 45. This plate includes a central opening 44 through which the mandrel is fed, and is supported in a vertical positionbehind .fthe mechanism 40. It has a series of holes 46 with belled orrounded edges (see FIG. 2a) arranged in a circle, there being a hole foreach wire, so that the wires are `grouped in an array :concentric with.the hose carcass on the mandrel as they pass through plate 45.

The -shaping mechanism 4t) includes a Wire-spacing place 48 which isparallel to the gathering plate 45 and alsohas an opening 50 for themandrel. This wire-spacing plate 48 has a series of holes 40 with belledor rounded edges (see FIG. 2b), arranged in a circle concentricallyabout its central opening 50. Each Wire extends through its respectivehole 49 and then over the upper surface of ring 52 which is positionedin front of spacing plate 48. The ring 52 is free to float or slideradially relative to the plate 48 and is supported entirely by the arrayof wires and is normally urged axially against the plate 48 by thetension in the wires. As shown in FIG. 2, the ring 52 is of toroidalshape and its size is such that its outer periphery does not exceed thediameter of the locus of centers of the holes 49 of plate 48. Thus theWires are fed through the holes 46 and 49 and are snubbed over the ring52, without scraping over any sharp edges. For making 1/2 inch internaldiameter hose as described in the preceding examples, the ring 52 isabout 1A; inch in cross sectional diameter and about 1% inches indiameter at its peripheral surface about which the Wires are deecte-d.

The wires are snubbed over the outer peripheral surface of the ring 52and then are converged through a central opening 54 of a die 55supported in a movable guide plate S6 of the shaping mechanism 40. Asshown, the mandrel also extends through the opening 54 of die 55. Theguide plate 56 is supported in `a guide way 57 and is in threadedengagement with a screw 58 which may be operated by a handle 59 to shiftthe guide plate 56 axially of the mandrel toward and away from thewire-spacing plate 48.

As the wi-res pass through the opening 54 in the die 55 they `arewrapped upon the hose carcass on the mandrel in the region surrounded bythe opening 54 at an angle to the axis of the mandrel proportional tothe rotational and axial lspeed of the mandrel. The opening 54 closelysurrounds the wrapped Wires, there being preferably no more than about1kg.; inch radial clearance between the outer diameter of the ply andthe opening 54. At the mouth of opening 54, through which the wires areconverged, there is a boss 60 having a convex wire-supporting surface 61which blends smoothly into the internal cylindrical surface of opening54. The wire-engaging surface 61 of boss 60 is of appreciably lesscurvature than the surface of ring 52 about which the wires aredeilected. The Wire-supporting surface of boss 60 may be formed on aradius equal to about the radius of opening 54. The `deflection impartedto the wires on the surface 61 of boss 60 is generally oblique to the-direction of the deflection imparted to the wires about the peripheryof ring 52. As a result of deflecting the wires over these surfacesunder appropriate tension, there is imparted to each wire .an inherenttendency to take the shape of a helix of controlled size. By adjustingthe axial distance between the guide plate 56 and the ring 52, thediameter and pitch of the neutral lay -convolutions of the helix inwhich the wires are formed can be regulated. When the guide plate 56 isadjusted close to the ring 52, more of the surface of the ring 52engages the wires, resulting in a more rigorous bending and deformationof the wires. A coil of smaller diameter is obtained when the guideplate 56 is positioned close to ring 52 than when the guide plate ismoved away from the ring. Ordinarily a tension of 1 to 5 pounds isimposed on each Wire by its respective let off.

In using equipment `of the type shown in FIG. 2 to make the hoseconstruction of FIG. 1, the tube 10 is rst sleeved over the madrel yandtaped to its ends. Then one end of the mandrel is inserted through thecentral openings 44, t) and S4 of the gathering plate 45 and the platesof the shaping mechanism, respectively, and into the chuck 34 of truck31 while the truck is positioned at its most leftward .position on rack32 as shown in FIG. 2. .The net fabric 17 in the form of a narrow tapeis then threaded through the openings `44, 50 and S4 from its supplyspool 65 and taped to the end of tube 1t) near the chuck 34. Then theends of all the wires forming the rst reinforcing ply 12 are threadedindividually from their respective spools 42 through the openings 46 inthe gathering plate 4S where they are spaced apart in an arrayconcentric with the mandrel. The wires are then threaded through theirrespective openings 49 in guide plate 48 and around the 'surface of thering 52, and then the wires are )converged through the central opening54 of die 55. The ends of these wires are then attached, preferably bytaping, to the tube adjacent the chuck 34. The position of guide plate56 is then adjusted toward ring 52 to establish the size of the inherenthelical shape to be imparted to the Wires.

When the motor 35 of the truck 31 is energized, the truck 31 proceedswith a uniform velocity rightward along the track 32 shown in FIG. 2.Simultaneously the chuck 34 is rotated to rotate the mandrel in adirection according to the direction of the helix desired for the wiresof the rst ply 12. The angular velocity of the mandrel will be adjustedrelative to the linear speed of the mandrel `so that the wires arewrapped at the desired angle to the longitudinal axis `of the mandrel.

The rotation of the mandrel and the advance of the truck 31 Orients thewires on the wire-supporting surfaces of the ring 52 and the boss 6i) ina manner to i-mpart an inherent helical shape of desired size. As thetruck 31 advances rightward, all the wires of ply 12 are Wound upon thenet fabric 17 which is wound helically upon tube 10 simultaneously withthe wrapping of the wires.

When the truck 31 has advanced a distance sufficient to bring theopposite end of the mandrel near the shaping mechanism 40, the truck is`stopped and the Wires are then taped securely to the mandrel near theright side of plate 56. After taping, the wires are cut oif and themandrel and truck 31 are repositioned as at the start of the first ply12 for the application of the second wire ply 13. The foregoingprocedure is then repeated to wrap the second ply 13 and each additionalwire ply except that the direction of rotation of the mandrel isreversed for successive plies. The insulating materials betweensuccessive plies such as the reinforcing fabric sheath 18 and the guminsulating layers 19 and 20 are applied simultaneously with the layingof the wire ply which surrounds them, in the same manner in which thenet fabric 17 is applied under the iirst wire ply 12. The guide plate 56may be readjusted relative to the ring 52 for the application of eachsuccessive wire ply to shape the wires to the helical size desired. Thedie S5 is removably supported in guide plate 56. For wrapping eachsuccessive ply a different die 55 having an opening 54 of appropriatesize for the -outer diameter of the particular ply is positioned in theguide 56.

Variations in the hose construction and the method of making this hosemay be made within the scope of the appended claims.

I claim:

1. A flexible hose comprising a tubular wall including rubber materialand at least two mutually concentric plies each consisting of amultiplicity of individual resilient flexible helical-shaped wires;

(A) all the wires of each ply:

(l) being formed to impart to them an inherent tendency to take theshape of a helix, and

(2) being disposed in their respective plies in parallel helicalconvolutions which extend at an :angle to the longitudinal axis of thehose within the range from about fifty-one (51) degrees to aboutfifty-nine (59) degrees;

(B) the helical convolutions in which the Wires of the radially innerply of said two plies are disposed being of opposite hand to the helicalconvolutions in which the wires lof the radially outer ply are disposed;

(C) all the wires yof said radially inner ply being dis- :posed in saidply in helical convolutions having a diameter and pitch which is notsubstantially greater than the diameter and pitch, respectively, of thehelilcal convolutions which said `Wires have an inherent tendency totake; and

(D) all the wires of said radially outer ply being disposed in said plyin helical convolutions the size of which differs from the size of thehelical convolutions which said wires have an inherent tendency to takein a manner to maintain the wires of the outer ply under a stressedcondition in which the wires exert gripping pressure on the underlyingadjacent portions of said tubular wall.

2. A hose as defined in claim 1 wherein the diameter of said helicalconvolutions in which the wires of said radially outer .ply are disposedin said ply is equal to or greater than the diameter of the helicalconvolutions 9 which `said wires have an inherent tendency to take; andthe pitch of said helical convolutions in which the Wires of saidradially outer ply are disposed in said ply is greater than the pitch ofthe helical convolutions which said Wires have an inherent tendency totake.

3. The method of making a exible Wire-reinforced hose which methodcomprises (A) providing a tubular hose carcass of rubber material;

(B) progressively wrapping in concentric relation upon said hose carcassat least two plies of resiliently exible wires in parallel helicalconvolutions,

(l) the direction of the helix being of opposite hand in said plies, and

(2) the wrapped convolutions of the Wires of each ply extending at anangle to the longitudinal axis within the range from about fty-one (51)degrees to about fifty-nine (59) degrees;

(C) progressively bending all the Wires of the radially inner ply Whilesaid Wires are being Wrapped to impart to them an inherent tendency totake the shape of a helix having a diameter and pitch not substantiallyexceeding the diameter and pitch of the convolutions in which said wiresare in fact wrapped; and

(D) progressively bending all the Wires of the radially router ply Whilethe wires are being wrapped to irnpart to them an inherent tendency totake the shape 0f a helix the size of the convolutions of which differsfrom the size of the convolutions in which said wires are wrapped in amanner to maintain the wires of the outer ply under a stressed conditionin which the wires exert gripping pressure on the underlying adjacentportions of said tubular wall.

References Cited by the Examiner UNITED STATES PATENTS LAVERNE D.GEIGER, Primary Examiner.

25 LEWIS I. LENNY, Examiner.

1. A FLEXIBLE HOSE COMPRISING A TUBULAR WALL INCLUDING RUBBER MATERIALAND AT LEAST TWO MUTUALLY CONCENTRIC PLIES EACH CONSISTING OF AMULTIPLICITY OF INDIVIDUAL RESILIENT FLEXIBLE HELICAL-SHAPED WIRES; (A)ALL THE WIRES OF EACH PLY: (1) BEING FORMED TO IMPART TO THEM ANINHERENT TENDENCY TO TAKE THE SHPAE OF A HELIX, AND (2) BEING DISPOSEDIN THEIR RESPECTIVE PLIES IN PARALLEL HELICAL CONVOLUTIONS WHICH EXTENDAT AN ANGLE TO THE LONGITUDINAL AXIS OF THE HOSE WITHIN THE RANGE FROMABOUT FIFTY-ONE (51) DEGREES TO ABOUT FIFTY-NINE (59) DEGREES; (B) THEHELICAL CONVOLUTIONS IN WHICH THE WIRES OF THE RADIALLY INNER PLY OFSAID TWO PLIES ARE DISPOSED BEING OF OPPOSITE HAND TO THE HELICALCONVOLUTIONS IN WHICH THE WIRES OF THE RADIALLY OUTER PLY ARE DISPOSED;(C) ALL THE WIRES OF SAID RADIALLY INNER PLY BEING DISPOSED IN SAID PLYIN HELICAL CONVOLUTIONS HAVING A DIAMETER AND PITCH WHICH IS NOTSUBSTANTIALLY GREATER THAN THE DIAMETER AND PITCH, RESPECTIVELY, OF THEHELICAL CONVOLUTIONS WHICH SAID WIRES HAVE AN INHERENT TENDENCY TO TAKE;AND (D) ALL THE WIRES OF SAID RADIALLY OUTER PLY BEING DISPOSED IN SAIDPLY IN HELICAL CONVOLUTIONS THE SIZE OF WHICH DIFFERS FROM THE SIZE OFTHE HELICAL CONVOLUTIONS WHICH SAID WIRES HAVE AN INHERENT TENDENCY TOTAKE IN A MANNER TO MAINTAIN THE WIRES OF THE OUTER PLY UNDER A STRESSEDCONDITION IN WHICH THE WIRES EXERT GRIPPING PRESSURE ON THE UNDERLYINGADJACENT PORTIONS OF SAID TUBULAR WALL.